Like the fortress it celebrates, this ponderous sequel to 2010's Live Free or Die moves slowly but gathers considerable momentum. Troy was just a huge asteroid until tycoon Tyler Vernon converted it into a battle station that humans could use to drive off the octopoid Horvath. Now the even nastier Rangora Empire wants to occupy Earth, so Vernon and his allies must use all their brains and gumption to carry the war into Rangora territory. Ringo shifts viewpoints among managers, such as Vernon and his immediate associates, and lower-level workers, including a hot-shot young female pilot and a welder who moves from construction to salvaging parts of wrecked alien warships. While humans of various backgrounds learn to cooperate, the feuding, reptilian Rangora elite are baffled by the bold, inventive American capitalists. The novel sometimes feels methodical to the point of plodding, but it climaxes in a satisfyingly grand space battle. (Jan.)